Muscle Types and Functions

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Muscle Types and Functions
Muscle Types and Functions By Julia Semprini

• By Julia Semprini

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Muscle Types

• Muscles are composed of muscle fibers- cells
  with many nuclei, bundles-contain many muscle
  fibers, thick and thin filaments-made of protein
  myosin and protein actin, and myofibrils (strands
  of protein) compact muscle and cause muscle
  contraction.
• The body uses three different types of muscles
  for a variety of purposes skeletal, cardiac, and
  smooth muscles.
• Having more fast and slow twitch muscle fibers
  determines what sports athletes excel at and how
  they condition and recover from injuries.

• Myocardial fibers conduct an electrical
  impulse to heart for contraction and pumping of
  blood.

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Three Muscle Classifications

• Skeletal muscles have bundles of muscle cell
  fibers.
• -striated (marked with lines or grooves), there
  are many nuclei and they have a more rounded
  appearance.
• Function contraction an abundant supply
  of nerves and blood vessels
• Skeletal muscle receives impulses from nerve
  cells for contraction
• Cardiac muscle is found only in the wall
  (myocardium) of the heart. Cardiac muscle fibers
  are striated and involuntary. It enables cardiac
  respiration and adequate blood supply which
  contains nutrients and oxygen.
• Smooth, or visceral muscle (of the main body
  organs), is unstriated and involuntary. It is
  primarily found in the walls of visceral organs
  (brain, heart and stomac, and blood vessels). It
  lines large airways to the lungs and large blood
  vessels. In the digestive system, smooth muscle
  contracts rhythmically forcing food molecules
  through the digestive tract.

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Muscle Memory

• As the brain and muscles adapt to training, the
  continued changes form muscle memory.
• Muscle memory is developed through repetition of
  motor skills (fine-writing, brushing teeth and
  gross-playing an instrument or swimming).
• -Activated by observation, orientation, decision
  and action
• A person who has had substantial muscular mass
  and then lost it due to injury or layoffs from
  training regains the majority of the muscle mass
  in a much shorter time than was originally
  required to develop it.
• The specific muscle proteins in the muscle were
  turned over by the body for energy production
  during non-use.  The muscle retains a higher than
  average number of nuclei that the previous
  exercises caused the body to create.  

http//www.pascalphoto.co.uk/perform/ballet_dancer
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A Golfers Perfected Swing

• A golfer must practice technique exercises for an
  efficient body alignment in a swing many times
  before movement becomes natural without thinking
  about it. (the shown lines referring to body
  angle and twist)

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Slow and Fast Twitch Muscle Fibers

• Slow twitch (Type I) muscle fibers, (slow
  oxidative fibers) and fast twitch (Type II)
  muscle fibers, (fast glycolytic fibers). Fast
  twitch fibers are further categorized into Type
  IIa and Type IIb fibers.
• Postural muscles of the neck, back, and leg have
  a higher amount of type I fibers, slow twitch.
• The differences between the two affect how
  muscles respond to training and physical
  activity.
• Fast twitch muscles- have more Type II fibers.
  Reactions take place using glycogen for anaerobic
  enzymes to produce immediate power. ( sprinting
  or kicking a soccer ball since he/she needs to
  quickly generate a lot of force)

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Genetic Makeup and Structure
http//www.abc.net.au/reslib/200710/r189045_708282
.jpg

• Human muscles contain a mixture of a genetic
  molecular code with a combination of slow and
  fast fiber types.
• Human body has about fifty percent slow twitch
  and fifty percent fast twitch fibers in most of
  the muscles used for movement.
• Tests on Olympic sprinters have shown that they
  possess about eighty percent fast twitch fibers,
  while those who excel in marathons tend to have
  80 percent slow twitch fibers.
• Slow Twitch Muscle Fibers- more capable at
  using oxygen to produce more fuel (known as ATP)
  for continuous, extended muscle contractions over
  a long period of time.
• Slow twitch fibers enable athletes to run
  marathons, bicycle for hours and practice tai
  chi, yoga or dance where movements and balances
  are held and slowly exerted

Endurance runner
Sprinter
Pilates
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Developing muscles

• You can develop your fast-twitch muscle fibers by
  practicing plyometric, yoga- type or complex
  training (combination of plyometrics and weights,
  with slow, longer reps) to build the fast muscle
  (IIa)
• Performing sprinting types of training to build
  the super-fast (IIb) where one can eventually
  release exercise-induced growth hormone.
• Cross training is the best way to develop all
  muscles and core strength-the powerhouse of the
  body, stability of spine, hip and leg movement)

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Strengthening both fast and slow twitch muscles

• Womens Health Magazine suggests using lighter
  weight for more sets and more repetitions to
  build slow twitch muscles.
• To strengthen your fast twitch fibers they
  suggest lifting fewer reps, like six, six, eight,
  using more weight.
• An invasive needle biopsy can be performed to get
  an accurate count of muscle fibers.
• Nutrition, motivation, environment and equipment
  advances (running shoes, swim suits, skis, and
  bicycles) are factors that allow for dramatic
  improvements in athletic performance.

Athletic training at higher elevations increases
number of red blood cells, decreases maximum
heart rate, improves acid and base balance and
more efficient oxygen to tissues
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Strengthening continued

• Genetics determine our strength, muscle size and
  muscle fiber composition (fast or slow twitch),
  anaerobic threshold, lung capacity, flexibility,
  and, to some extent endurance.
• Limitation for endurance athletes cardiac
  capacity, or the hearts ability to transport
  enough oxygen (via the bloodstream) to the
  working skeletal muscles.
• Genetics may also determine how we respond to
  training, diet and other external factors such as
  healing from an injury.

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Bibliography

• http//www.brianmac.co.uk/muscle.htm
• http//muscle.ucsd.edu/musintro/contractions.shtml
  
• http//www.innerbody.com/image/musc01.html
• http//www.isokinetics.net/advanced/musclefibertyp
  es.htm
• http//sportsmedicine.about.com/od/anatomyandphysi
  ology/a/MuscleFiberType.htm